In removing himself, Sessions put acting Deputy Attorney General Dana Boente in charge leading the investigation. Boente was nominated by former President Barack Obama. This morning Chuck said if Sessions does not resign he must recuse and give the investigation to Boente. No the Minority does not have the authority but he knew he it would fall to Boente if he could pressure Sessions.
But what do I know as you pointed out I am just a moron.
What investigation? There is none going on, as far as I know.
Boente may have been nominated by Obama, but Obama also changed the Justice Department protocols so that Boente would not be a successor to the U.S. Attorney General in matters like this. It was Trump who signed the executive order reversing Obama's move.
P.S. -- Boente is a political appointee, so Trump can fire him tomorrow if he wants to.